// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/base/histograms.h"

#include <limits>

#include "testing/gtest/include/gtest/gtest.h"

using base::TimeDelta;
using Sample = base::HistogramBase::Sample;

namespace cc {

class ScopedUMAHistogramAreaTimerBaseTest : public ::testing::Test {
protected:
    void ExpectValidHistogramValues(base::TimeDelta elapsed,
        int area,
        Sample expected_time_microseconds,
        Sample expected_pixels_per_ms)
    {
        Sample time_microseconds;
        Sample pixels_per_ms;
        ScopedUMAHistogramAreaTimerBase::GetHistogramValues(
            elapsed, area, &time_microseconds, &pixels_per_ms);
        EXPECT_EQ(expected_time_microseconds, time_microseconds);
        EXPECT_EQ(expected_pixels_per_ms, pixels_per_ms);
    }
};

namespace {

    TEST_F(ScopedUMAHistogramAreaTimerBaseTest, CommonCase)
    {
        ExpectValidHistogramValues(TimeDelta::FromMicroseconds(500), 1000, 500, 2000);
        ExpectValidHistogramValues(TimeDelta::FromMicroseconds(300), 1000, 300, 3333);
    }

    TEST_F(ScopedUMAHistogramAreaTimerBaseTest, ZeroArea)
    {
        ExpectValidHistogramValues(TimeDelta::FromMicroseconds(500), 0, 500, 0);
    }

    TEST_F(ScopedUMAHistogramAreaTimerBaseTest, ZeroTime)
    {
        // 1M pixels/ms, since the time is limited to at least 1us.
        ExpectValidHistogramValues(TimeDelta(), 1000, 1, 1000000);
    }

    TEST_F(ScopedUMAHistogramAreaTimerBaseTest, ZeroTimeAndArea)
    {
        ExpectValidHistogramValues(TimeDelta(), 0, 1, 0);
    }

    TEST_F(ScopedUMAHistogramAreaTimerBaseTest, VeryLargeTime)
    {
        ExpectValidHistogramValues(TimeDelta::FromHours(24), 1000,
            std::numeric_limits<Sample>::max(), 0);
    }

    TEST_F(ScopedUMAHistogramAreaTimerBaseTest, VeryLargeArea)
    {
        ExpectValidHistogramValues(TimeDelta::FromMicroseconds(500), 1000000000, 500,
            2000000000);
        ExpectValidHistogramValues(TimeDelta::FromMicroseconds(1000),
            std::numeric_limits<int>::max(), 1000,
            std::numeric_limits<Sample>::max());
    }

} // namespace
} // namespace cc
